Catheters comprise tube-like members inserted into the body for diagnostic or therapeutic medical reasons. One of the therapeutic procedures applicable to the present invention is known as percutaneous transluminal coronary angioplasty (PTCA). The first PTCA procedure was developed in approximately 1976-1977 by Dr. Andreas Gruntzig. This fixed wire system featured a core or guidewire fixed within the catheter to stiffen it so that it could be pushed into position in the vascular system. Blockage in a coronary artery could be reduced by positioning the balloon dilatation catheter across from the blockage and inflating the balloon causing the blockage to decrease.
If a catheter must be exchanged for one of a different size, an over-the-wire system is advantageous because the guidewire can be left in place. The catheter is withdrawn over the guidewire and another catheter slid into place over it. A disadvantage of this exchange procedure is that it is difficult to keep the guidewire in place, since removing the catheter requires removal of the guidewire and subsequent recrossing of the stenosis. Alternatively a very long "exchange" guidewire of approximately 300 cm can be used. This is difficult to handle because such a procedure requires two operators who must be in communication during the procedure. This requires more time and risks contamination by dropping the guidewire from the sterile field. An alternative to these long exchange guidewires is a two-part guidewire. This is also undesirable because it requires additional time to assemble and may be too thick to allow smooth exchanges.
Rapid exchange catheters were developed to respond to the disadvantage of the long "change" wire in over-the-wire systems. These catheters have shorter guidewire lumens passing through the balloon so that the guidewire exits from the catheter closer to the balloon than to the proximal end of the catheter. This enables the physician to anchor or hold the guidewire as he or she removes the catheter from the body with the exchange occurring over the shorter guidewire lumen. Various systems of rapid exchange catheters have been developed as follows.
U.S. Pat. No. 4,597,755, to Samson, et al., for "Large Bore Catheter Having Flexible Tip Construction" discloses "[a] balloon flushing wire or tube 46 . . . mounted in the side arm 43 and extends through the passage 38 into the distal extremity of the balloon 37 . . . ". See col. 3, lines 26-28. ". . . [A]11 the air within the balloon is forced out through the balloon flushing tube or wire 46." See col. 3, lines 43-45".
U.S. Pat. No. 4,748,982 to Horzewski, et al., "Reinforced Balloon Dilatation Catheter with Slitted Exchange Sleeve and Method" discloses a short guidewire lumen entering proximal to the balloon and exiting at the distal end of the balloon.
U.S. Pat. No. 4,762,129 to Bonzel and continuation U.S. Pat. No. 5,232,445, for "Dilatation Catheter" was one of the first rapid exchange catheters. It discloses a "first tube having sufficient stiffness that the second tube and expandable balloon can readily be advanced . . . along the guide wire by exerting a pushing . . . force upon the first tube, in combination with the elongated guide wire." See col. 4, lines 6-11.
U.S. Pat. No. 4,927,413 to Hess, for "Catheter for Balloon Angioplasty" discloses a ". . . core means 20a (which is) withdrawn or advanced to vary the shaft stiffness . . . " see col. 5, lines 65-67. "It is understood that shaft 12 is sealed with respect to passage 18, such as by use of a plastic covering, so that balloon 34 may be inflated." See col. 4, lines 41-43 and FIG. 4.
U.S. Pat. No. 4,968,300 to Moutafis, et al., for "Balloon Stretch Mechanism" discloses a support member 103 extending through the balloon.
U.S. Pat. No. 5,180,367 to Kontos, et al., for "Procedure and Balloon Catheter System for Relieving Arterial or Veinal Restrictions Without Exchanging Balloon Catheters" discloses a short guidewire lumen running either through the balloon as in FIG. 3 or running along the outside of the balloon as in FIG. 5.
WO Patent 92/17236 to Scopton, et al., for "Adjustably Stiffenable Convertible Catheter Assembly" discloses a convertible-type balloon catheter having at least three lumens. The first lumen accommodates the stiffening mandrel. The second lumen is the inflation lumen and the third lumen functions as a lumen for an over-the-wire mode and a rapid exchange mode, using part of the lumen for a guidewire and part of that lumen for catheter stiffening assistance.